In
this design there is NO LOSS of compressed air. Time cycle
is 4+4 hours with (-) drying towers filled with SILICA
GEL desiccant. For regeneration, a centrifugal air blower
and an electrical heater is provided. Desiccant is heated
upto 200oC by hot air for complete regeneration.
These dryers
are bulky in size and the power consumption is almost double
as compared to "INTERNALLY HEAT REACTIVATED TYPE DRYER".
In capacities less than 500 NM3/hr these are uneconomical
and not recommended. Also, since regeneration of the desiccant
is by atmospheric air, these dryers give Dew Point only upto
(-) 40oC.
Cost wise
these Airdryers are 100% more costly as compared to
"Internally
Heat Reactivated Type Dryers".
One should
go for this type of Dryer only when loss of compressed air
during regeneration is not acceptable and Dew Point required
is not critical. These are recommended for capacities above
500 NM3/hr only. Operating pressure can be from
1 kg/cm2g to 50 kg/cm2g.
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